U.S. patent application number 11/411618 was filed with the patent office on 2007-11-01 for foaming-resistant hydrocarbon oil compositions.
This patent application is currently assigned to Cytec Surface Specialties. Invention is credited to John Zheng Fang, Ming Zhao.
Application Number | 20070254819 11/411618 |
Document ID | / |
Family ID | 38649042 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070254819 |
Kind Code |
A1 |
Fang; John Zheng ; et
al. |
November 1, 2007 |
Foaming-resistant hydrocarbon oil compositions
Abstract
A composition of matter resistant to foaming comprising a
hydrocarbon oil and an acrylate copolymer dispersed in the said
hydrocarbon oil, which acrylated copolymer contains at last one
polymerised fluorinated (meth)acrylate monomer wherein not more
than three neighbouring carbon atoms in the said fluorinated
(meth)acrylate monomer carry one or more fluorine substituents
Inventors: |
Fang; John Zheng;
(Parsippany, NJ) ; Zhao; Ming; (East Longmeadow,
MA) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
Cytec Surface Specialties
|
Family ID: |
38649042 |
Appl. No.: |
11/411618 |
Filed: |
April 26, 2006 |
Current U.S.
Class: |
508/469 |
Current CPC
Class: |
C10N 2040/04 20130101;
C10N 2030/18 20130101; C10N 2030/16 20130101; C10N 2040/042
20200501; C10M 2213/04 20130101; C10M 147/04 20130101 |
Class at
Publication: |
508/469 |
International
Class: |
C10M 145/14 20060101
C10M145/14 |
Claims
1. A composition of matter resistant to foaming comprising a
hydrocarbon oil and an acrylate copolymer dispersed in the said
hydrocarbon oil, which acrylate copolymer contains at least one
polymerised fluorinated (meth)acrylate monomer wherein not more
than three neighbouring carbon atoms in the said at least one
fluorinated (meth)acrylate monomer carry one or more fluorine
substituents.
2. The composition of matter of claim 1, wherein the said at least
one fluorinated (meth)acrylate monomer in the acrylate copolymer is
selected from the group consisting of
2,2,2-trifluoroethyl(meth)-acrylate,
3,3,3-trifluoropropyl(meth)acrylate,
2,2,3,3,3-pentafluoropropyl(meth)acrylate,
2,2,2-trifluoroisopropyl(meth)acrylate and
2,2,2,2',2',2'-hexafluoroisopropyl(meth)acrylate.
3. The composition of matter of claim 1, wherein the said at least
one fluorinated (meth)acrylate monomers is copolymerised with at
least one non-fluorinated olefinically unsaturated monomer selected
from the group consisting of alkyl acrylates in which the alkyl
radical is linear, branched or cyclic and has from 1 to 18 carbon
atoms, alkyl methacrylates in which the alkyl radical in which the
alkyl radical is linear, branched or cyclic and has from 1 to 18
carbon atoms, alkyl esters of maleic and fumaric acids in which the
alkyl radical is linear, branched or cyclic and has from 1 to 18
carbon atoms, vinyl esters of aliphatic carboxylic acids having
from two to 20 carbon atoms, alkyl vinyl ethers and alkyl vinyl
ketones in which the alkyl radical is linear, branched or cyclic
and has from 1 to 18 carbon atoms, styrene and substituted
styrenes.
4. The composition of matter of claim 3, wherein in the said
acrylate copolymer, the mass fraction of the said at least one
alkyl acrylate in which the alkyl radical is linear, branched or
cyclic and has from 1 to 18 carbon atoms is at least 50%.
5. The composition of matter of claim 1, wherein the mass fraction
of fluorine in the said acrylate copolymer is from 0.1% to 5%.
6. The composition of matter of claim 1, wherein the fluorinated
(meth)acrylate monomer is 2,2,2-trifluoroethyl methacrylate.
7. The composition of matter of claim 4, wherein the said at least
one alkyl acrylate is are selected from the group consisting of
ethyl acrylate, 2-ethylhexyl acrylate, and mixtures of these.
8. The composition of matter of claim 1, wherein the weight-average
molar mass of the acrylate copolymer is from 20 kg/mol to 100
kg/mol.
9. The composition of matter of claim 1, wherein the mass fraction
of the acrylate copolymer in the mixture with the hydrocarbon oil
is from 20 mg/kg to 500 mg/kg.
10. The composition of matter of claim 1, wherein the mass fraction
of the said at least one fluorinated (meth)acrylate monomer in the
acrylate copolymer is from 0.1% to 10%.
Description
FIELD OF THE INVENTION
[0001] This invention relates to foaming-resistant hydrocarbon oil
compositions, and more particularly to a polymeric anti-foaming
agent in such oil.
BACKGROUND OF THE INVENTION
[0002] Suppression of foam generated in using hydrocarbon oils is
of major importance, additives in small effective amounts in such
oils being widely used for this purpose. Customary additives are
the acrylate polymers as disclosed in U.S. Pat. No. 3,166,508 to
Fields. As is noted there, other additives in such oils used to
improve oil-related performance can aggravate the tendency to foam,
and a continuing need exists to inhibit such undesirable foaming
over a wide range of use conditions, particularly in new
hydrocarbon oil formulations. Foam-reducing agents comprising
fluorine-containing acrylate copolymers with longer-chain
fluorinated alkyl acrylates as comonomers as have been known, i. a.
from EP 1 029 030 B1. As there is a concern regarding the
bio-accumulation of longer-chain fluorinated compounds, such as
those comprising perfluoro octyl moieties, there is a need to
provide anti-foaming agents that do not exhibit similar
bio-accumulation.
SUMMARY OF THE INVENTION
[0003] Improved hydrocarbon oil compositions have been developed
with enhanced resistance to foaming. Accordingly, a principal
object of this invention is to provide compositions of hydrocarbon
oil which resist foaming over a wide range of use conditions.
Another object is to provide an acrylate polymer anti-foaming agent
for use in such improved foaming-resistant compositions, which
acrylate polymer does not show any propensity to bio-accumulation.
Other objects of this invention will in part be obvious and will
appear from the following description and claims. These and other
objects are accomplished by providing a composition of matter
resistant to foaming comprising a hydrocarbon oil having a tendency
to foam and a foam-inhibiting amount dispersed in the hydrocarbon
oil of an acrylate copolymer containing at least one polymerised
fluorinated alkyl(meth)acrylate monomer wherein not more than three
neighbouring carbon atoms carry one or more fluorine
substituents.
[0004] When reference is made to (meth)acrylates in the context of
this invention, this expression shall encompass both acrylates and
methacrylates. When reference is made to an acrylate copolymer,
this is deemed to encompass all copolymers having a mass fraction
of at least 20% of moieties derived from (meth)acrylate
monomers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0005] Fluorine in acrylate copolymer anti-foaming additives
significantly improves resistance to foaming of hydrocarbon oils.
Such fluorine is provided by the presence of at least one
polymerised fluorinated (meth)acrylate as a monomer component of
the acrylate copolymer. The amount of such bound fluorine in the
acrylate copolymer effective to inhibit foaming varies with the
composition or formulation of the hydrocarbon oil in which the
acrylate copolymer is dispersed. A mass fraction of fluorine in the
acrylate copolymer of up to about 30% is generally adequate as
anti-foaming agent for most hydrocarbon oils, with mass fractions
of from about 0.10% to about 10% being preferred, and mass
fractions of from about 0.50% to 5% being most preferred. The
amount of the at least one fluorinated (meth)acrylate monomer is
preferably chosen such that the mass fraction of the said at least
one fluorinated (meth)acrylate monomer in the acrylate copolymer is
from 0.1% to 10%.
[0006] Fluorinated (meth)acrylate monomers used in the synthesis of
the said acrylate copolymers are preferably esters of acrylic or
methacrylic acids with fluorinated alkanols, which alkanols may be
linear or branched, and may also comprise hetero atoms such as
oxygen, nitrogen or sulphur. These alkanols may not have more than
two adjacent carbon atoms which carry at least one fluorine atom.
The at least one fluorinated (meth)acrylate monomer in the acrylate
copolymer has not more than three, preferably not more than two,
neighbouring carbon atoms in the alkyl group which carry one or
more fluorine atom. This means that in the alkyl chain, there may
be moieties like --CF.sub.2--CF.sub.2--CF.sub.2-- or
--CF.sub.2--CF.sub.2-- or --CF.sub.2-- or
--CFR.sup.1--CFR.sup.2--CFR.sup.3-- or --CFR.sup.4--CFR.sup.5-- or
--CFR.sup.6--
[0007] where carbon atoms directly bound to these moieties may not
carry fluorine substituents, R.sup.1 to R.sup.7 standing for aryl
groups, alkoxy groups, acyl groups, and alkyl groups that do not
carry fluorine atoms in the carbon atom immediately adjacent to the
binding site. Sequences with more than three sequential
--CF.sub.2-- groups or --CFR.sup.7-- groups are ruled out. The
fluorinated (meth)acrylate monomers that can be used in the
synthesis of the said acrylate copolymers are preferably selected
from the group consisting of 2,2,2-trifluoroethyl(meth)acrylate,
3,3,3-trifluoropropyl(meth)acrylate,
2,2,3,3,3-pentafluoropropyl(meth)acrylate,
2,2,2-trifluoroisopropyl(meth)acrylate and
2,2,2,-2',2',2'-hexafluoroisopropyl(meth)-acrylate, with
trifluoroethyl(meth)acrylate being particularly preferred.
Especially preferred in the context of the present invention is
trifluoroethyl methacrylate.
[0008] The said at least one fluorinated (meth)acrylate monomer is
copolymerised with at least one non-fluorinated olefinically
unsaturated monomer, such as an alkyl acrylate in which the alkyl
radical is linear, branched or cyclic and has from 1 to 18 carbon
atoms, an alkyl methacrylate in which the alkyl radical is linear,
branched or cyclic and has from 1 to 18 carbon atoms, an alkyl or
dialkyl ester of maleic or fumaric acid in which the alkyl radical
is linear, branched or cyclic and has from 1 to 18 carbon atoms, a
vinyl ester of an aliphatic carboxylic acid having from two to
twenty carbon atoms, an alkyl vinyl ether in which the alkyl
radical is linear, branched or cyclic and has from 1 to 18 carbon
atoms, and an alkyl vinyl ketone in which the alkyl radical is
linear, branched or cyclic and has from 1 to 18 carbon atoms,
styrene and a substituted styrene such as vinyl toluene.
[0009] Of these comonomers, the first-named alkyl acrylates are
particularly preferred, and a mass fraction of moieties derived
therefrom of at least 50% in the copolymer is especially preferred.
It is preferred to use an acrylic ester of an alkanol which is
linear or branched, and has from two to ten carbon atoms, such as
ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec. butyl
acrylate, 1- and 2-hexyl acrylate, 1-octyl acrylate, 2-ethylhexyl
acrylate, and 1-decyl acrylate. Mixtures of such esters are
particularly preferred, such as mixtures of ethyl acrylate and
2-ethylhexyl acrylate.
[0010] The molar mass (weight average M.sub.w) of the acrylate
copolymer defoaming agent can vary within broad limits and is
generally from about 10,000 g/mol to about 250,000 g/mol (from 10
kg/mol to 250 kg/mol), preferably about 20,000 g/mol to 100,000
g/mol (from about 20 kg/mol to 100 kg/mol). At very high molar
masses of in excess of 250 kg/mol, the acrylate copolymer tends to
settle out in many hydrocarbon oils and lose its defoaming
effectiveness which relies on being finely dispersed in the oil. If
M.sub.w is lower than about 10 kg/mol it tends to dissolve in, and
form the same phase as, the oil and therefore cannot be a defoamer.
The acrylate copolymer antifoaming agents containing polymerised
fluorinated (meth)acrylate monomer are effective at very low
concentrations in the hydrocarbon oil, i. e. at a mass fraction of
less than about 1500 mg/kg ("1500 ppm"). Mass fractions of from 20
mg/kg to 500 mg/kg are preferred, but this may be varied depending
upon the nature of the oil, mass fractions less than 200 mg/kg by
weight usually being sufficient. Heavy oils and oils containing
foam-inducing adjuvants require more of the acrylate copolymer
defoaming agent than do base oils with lesser foaming
characteristics.
[0011] The acrylate copolymer defoaming agents are preferably added
to the hydrocarbon oil as a solution in a hydrocarbon solvent. The
foaming-inhibiting effect of the acrylate copolymers is not
materially affected by the presence of other adjuvants in the
hydrocarbon oil. Since the acrylate copolymers are present in the
oils in only very small quantities, the use in the oil of very
acidic or very basic adjuvants has substantially no effect on
performance of the antifoam additives. Compositions of hydrocarbon
oils containing the present defoaming agents are storage-stable
over long time periods and also when subjected to heat and pressure
during operating use conditions. Hydrocarbon oils rendered
substantially foaming-resistant by incorporating a foam-inhibiting
quantity of the present anti-foaming acrylate copolymers are
synthetic or petroleum stocks of varying viscosities such as
lubricating oils for internal combustion engines and motors, diesel
fuels, lubricants and pressure transfer media, e. g., industrial
lubricants, process oils, hydraulic oils, turbine oils, spindle
oils, journal bearing oils, pneumatic tool lubricants, etc. They
may be synthetic or natural hydrocarbons of any type, i. e.
paraffinic, naphthenic, aromatic or blended.
[0012] The acrylate copolymers of the invention are prepared by
mass, emulsion or solution polymerisation in the presence of a
free-radical catalyst and, optionally, known polymerisation
regulators (chain transfer agents). When mass polymerised, mixtures
of monomers and free-radical catalyst are agitated at 35.degree. C.
to 150.degree. C. until polymerisation is substantially complete.
In emulsion polymerisation, an emulsion of monomers in an aqueous
solution with suitable emulsifying agents such as soap or
alkyl-substituted sulfosuccinate is polymerised at from 25.degree.
C. to the boiling temperature of water. In solution polymerisation,
the monomers are dissolved in an inert liquid, and the solution is
agitated in the presence of a catalyst at from 25.degree. C. to the
boiling temperature of the solution. Solvents are generally
substantially neutral organic liquids which are not affected during
the polymerisation process, e. g. aliphatic, aromatic alkyl
aromatic or alicyclic hydrocarbons such as hexane, benzene,
ethylbenzene or cyclohexane; ketones such as methyl ethyl ketone or
acetone; esters such as ethyl acetate or methyl propionate;
chlorinated hydrocarbons such as carbon tetrachloride or
chloroform; ethers such as diethyl ether or dioxane.
[0013] Since the polymers are used as oil additives, polymerisation
in a solvent with no adverse effect on the hydrocarbon oil
facilitates adding the resulting polymer solution directly to the
oil without first separating the polymer from the reaction medium.
However, at completion of polymerisation if the polymer solution is
too viscous for convenient handling, the solvent can be stripped
away and the solid polymer redissolved in another solvent in a mass
fraction in the resulting solution which is typically from 30% to
60%, providing a less viscous, more readily handled solution
tailored for sale to the hydrocarbon oil formulator. Other reasons
to change the solvent are to provide one which is more
environmentally friendly, is safer in having a higher flash point
and/or is less odorous.
[0014] Polymerisation of the acrylate polymers can be conducted in
the presence of polymerisation modifiers acting on the solubility
of the polymers. Such modifiers include chain transfer agents such
as alkyl mercaptans, e. g. tert-butyl mercaptan or n-dodecyl
mercaptan; the polyhaloalkanes such as carbon tetrachloride,
chloroform or bromo-form; the nitroalkanes such as nitroethane or
2-nitropropane; liquid hydrocarbons such as toluene, ethylbenzene,
or kerosene, etc. The chain transfer agent may also be the solvent
which is used during the reaction or it may be incorporated as an
additional solvent, e. g. dioxane, acetone, isopropanol, paraffin
hydrocarbons, etc.
[0015] Useful catalysts include organic peroxide compounds such as
acetyl, benzoyl, lauroyl and stearoyl peroxides and tert.-butyl and
cumene hydroperoxides; inorganic peroxo compounds such as hydrogen
peroxide, sodium perborate, and potassium persulfate; diazo
compounds such as azo-bis-isobutyronitile, alpha,
alpha-azodiiso-butyramide, etc.
[0016] The polymerisation reaction may be conducted in batch mode,
e. g. by agitating the reactants (which are charged initially at
once or partially metered in over time during polymerisation) at a
temperature of from 80.degree. C. to 150.degree. C. until the
reaction is complete, or continuously by constantly removing
polymer while replenishing one or more of the monomers, catalyst
and chain transfer agent. When operating batchwise the polymeric
reaction product is usually separated from the reaction mixture by
distilling off solvent and any unreacted starting material.
However, as noted, separation may not be necessary when the
reaction mixture as a solution of polymer in solvent is used
directly as additive to the hydrocarbon oil. The invention is
further described in the following illustrative Examples which are
not intended to limit the invention. All relative quantities
measured in "%" are mass fractions (ratio of the mass of the
substance considered and the mass of the mixture).
EXAMPLE 1
Defoamer with a Mass Fraction of 2,2,2-trifluoroethyl methacrylate
in the copolymer of 1%
[0017] This example illustrates the preparation of radical solution
polymerisation process comprising trifluoroethyl methacrylate:
[0018] A 2000 ml glass reactor was initially charged with ethyl
acetate (102.7 g) and isopropyl alcohol (25.7 g). The contents were
heated to about 80.degree. C. A mixture of .RTM.vazo-64
(2,2'-azobis-2-methylbutyronitrile, E. I., DuPont de Nemours &
Co., 1.15 g), ethyl acetate (20.5 g), isopropyl alcohol (5.1 g),
ethyl acrylate (103.0 g), 2-ethylhexyl acrylate (320.0 g), and
2,2,2-trifluoroethyl methacrylate (4.05 g) was then gradually added
to the reactor during two hours. After addition of the first
mixture, the system was held at the set temperature under stirring
for one hour. The second mixture, comprising .RTM.vazo-64 (4.02 g),
ethyl acetate (39.8 g), isopropyl alcohol (9.9 g), ethyl acrylate
(137.0 g), 2-ethylhexyl acrylate (240.0 g), and
2,2,2-trifluoroethyl methacrylate (4.05 g), was then added to the
reactor during two hours. The mixture was left to react for another
one and a half hours. Solvent, residual monomers, and other
by-products from initiation were stripped off. The resulting
polymer was then cooled to 65.degree. C. and filtered. A colourless
viscous polymer was obtained in a yield of 98.9%. The weight
average molar mass was 71,800 g/mol, determined by gel permeation
chromatography using polystyrene as standard. The mass fraction of
fluorine in the copolymer was 0.34%.
EXAMPLE 2
Comparative, Defoamer with a Mass Fraction of .RTM.Zonyl TA-N in
the copolymer of 1%
[0019] Example 1 was repeated, but 2,2,2-trifluoromethacrylate was
replaced by the same mass of .RTM.Zonyl TA-N (commercial
fluoroalkyl acrylate from E. I. du Pont de Nemours and Company,
comprising mass fractions of
C.sub.6F.sub.13--CH.sub.2--CH.sub.2--O-- residues of at most 6%, of
C.sub.8F.sub.17--CH.sub.2--CH.sub.2--O-- residues of (50.+-.3)%, of
C.sub.10F.sub.21--CH.sub.2--CH.sub.2--O-- residues of (29.+-.2)%,
of C.sub.12F.sub.25--CH.sub.2--CH.sub.2--O-- residues of (11.+-.2)
%, and of C.sub.14F.sub.29--CH.sub.2--CH.sub.2--O-- and higher
residues of at most 4%). The mass fraction of fluorine in the
copolymer was 0.64%.
EXAMPLE 3
Foaming Resistance
[0020] The test method evaluating foaming resistance is a modified
form of ASTM D892-92. A hydrocarbon oil sample containing finely
dispersed antifoaming agent is blown with air at a constant rate of
(94.+-.5) ml/min for 5 min at (24.0.+-.0.5).degree. C. and then
allowed to settle. The volume of foam generated above the oil level
is measured, and the time needed to fully collapse the foam is
measured. Performance in this phase is recorded under Sequence
(abbreviated as "Seq.") I in the following tables. This test is
repeated on a second sample at a temperature of
(94.0.+-.0.5).degree. C., with results shown under "Seq. II" in the
tables. After the foam from Seq. II has collapsed, the same sample
is cooled to 24.degree. C., and the procedure for Seq. I repeated
with results shown under "Seq. III". The same sample from Seq. III
test is then heated to (153.0.+-.0.5).degree. C. and the Seq. I
procedure is repeated with a higher air flow of (200.+-.5) ml/min,
with results of this rather severe high temperature test shown
under "Seq. IV".
[0021] 2.5 g of a solution of the defoaming agent of Example 1 in
an aliphatic hydrocarbon solvent (.RTM.Shellsol D 40, mixture of
C.sub.9-- to C.sub.11-- paraffins and naphthenes, 40 g of polymer
in 100 g of solution) was diluted with further solvent to 50 g. The
mass fraction of defoamer in this dilute solution was now 2% (2
g/100 g). 0.8 g of this defoamer solution were added to 200 g of
test oil. This test oil blend was vigorously shaken for three
minutes to finely disperse the defoamer solution in the oil.
Foaming resistance was then measured using different hydrocarbon
oil compositions under the various sequences of the noted test
method. These hydrocarbon oil composition were prepared by adding a
quantity of this test oil blend to the hydrocarbon oil. The test
oils used were compositions corresponding to commercial grades of
industrial oils, ATM (automatic transmission) fluids, and gear
oils, but without defoamer added. Usually, the mass fraction of
defoamer (conventional defoamer based on non-fluorinated acrylate
copolymers) in such oils is about 200 mg/kg ("200 ppm").
[0022] In this test, the hydrocarbon oils used were a commercially
available industrial oil, an automatic transmission fluid, and a
gear oil, in each case without the usual addition of defoaming
agent. The defoaming agent of the invention is the acrylate
copolymer of Example 1 ("Ex. 1"). For comparison purposes, a
similar composition was prepared using the same mass fraction of
the acrylate copolymer of Example 2. "Comp" refers to .RTM.PC-1644,
a conventional non-fluorinated polyacrylate defoaming agent,
available from Cytec Industries, Inc. The mass fraction w of the
defoaming agent in the hydrocarbon oil composition is calculated as
the ratio of the mass m.sub.A of the defoaming agent and the mass
m.sub.o of the hydrocarbon oil composition, it is measured in
"mg/kg" equivalent to "ppm". The volume V of foam as measured is
stated in ml (millilitres), and the collapse time t is stated in s
(seconds). Testing was done at an extremely low mass fraction of
defoaming agent in the hydrocarbon oil composition (30 mg/kg and 50
mg/kg), compared to that ratio which is generally in use (200
mg/kg). The purpose of choosing this low mass fraction was to
ascertain any difference between developmental materials and
current commercial defoaming agents. TABLE-US-00001 TABLE 1
Industrial oil Defoaming agent Seq. I Seq. II Seq. III Kind
w/(mg/kg) V/ml t/s V/ml t/s V/ml t/s None 330 192 35 12 300 30
Comp. 30 0 0 20 3 0 0 Ex. 2 30 0 0 20 0 0 0 Ex. 1 30 0 0 15 0 0
0
[0023] TABLE-US-00002 TABLE 2 Automatic transmission fluid
Defoaming agent Seq. I Seq. II Seq. III Seq. IV Kind w/(mg/kg) V/ml
t/s V/ml t/s V/ml t/s V/ml t/s None 440 310 60 41 390 316 550 19
Comp. 50 360 279 50 22 340 276 530 15 Ex. 2 50 90 24 50 25 180 72
140 12 Ex. 1 50 40 13 50 33 180 69 100 16
[0024] TABLE-US-00003 TABLE 3 Gear oil Defoaming agent Seq. I Seq.
II Seq. III Seq. IV Kind w/(mg/kg) V/ml t/s V/ml t/s V/ml t/s V/ml
t/s None 40 43 360 135 290 >300 350 28 Comp. 50 0 0 0 0 0 0 530
41 Ex. 2 50 0 0 0 0 0 0 260 42 Ex. 1 50 0 0 0 0 0 0 200 42
[0025] The above data illustrates the significant foaming-resistant
results in various hydrocarbon oils of the acrylate copolymer
defoaming agents of the invention containing a mass fraction of
about 0.34% of chemically incorporated fluorine (Example 1) in
comparison with the fluorinated acrylate copolymer of example 2
(with a mass fraction of about 0.64% of chemically incorporated
fluorine) and a pure (i. e. non-fluorinated) polyacrylate defoaming
agent. Comparing with pure polyacrylate defoaming agents,
fluorine-containing defoaming agents (ex. 1 and 2) showed much
improved high temperature efficiencies as well as general defoaming
characteristics. Comparing with the defoaming agent of Example 2
with a bulky fluorine containing moiety having more than three
adjacent carbon atoms which bear at least one fluorine substituent,
the acrylate copolymer defoaming agent of example 1 comprises a
short chain fluorinated monomer, having not more than three
adjacent carbon atoms which bear at least one fluorine substituent.
Unexpectedly, such acrylate copolymers exhibit an even better high
temperature defoaming performance and improved shelf life stability
in hydrocarbon oils containing the said defoaming agent, as
compared to defoaming agents comprising the afore-mentioned
longer-chain fluorinated materials.
* * * * *